Radar?

[John Baker]

Another thread set me off on this tangent. Years ago, pre-GPS, I was sailing toward the entrance of San Diego Bay in fairly dense fog. There is a buoy a few miles out called "The Whistler". The trick was to find the whistler then chart your way into the bay.

Anyway, as I was blundering around out there trying to hear that spooky moaning sound the whistler emitted, my mast started "pinging" like in those old submarine war movies. I was able to determine that I was not under water, so I ruled out sonar, and assumed it was radar.

My question is, if radar will make a "pinging" noise off an aluminum mast, why doesn't it do that to an airplane?

John

 

[TMetzinger]

I think that was a lanyard or halyard or something else making that noise, not radar.

 

[Skip Miller]

My question is, if radar will make a "pinging" noise off an aluminum mast, why doesn't it do that to an airplane?

John

My guess is that you heard Sonar. The underwater sound energy was impacting the hull/keel and the sound was being transmitted to the mast which just happened to have a sympathetic harmonic vibration frequency.

I've never heard of electromagnetic radiation creating directly an audible sound. But - this is a fact free opinion!

-Skip

 

[John Baker]

I think that was a lanyard or halyard or something else making that noise, not radar.

Definitely not a halyard or anything else smacking against the mast. I was under full sail, the only halyard not being used was the spinnaker.

This was that absolute pinging noise you hear in those old submarine movies. Very loud, very distinct, evenly spaced. It was coming from a ship, that was either leaving or entering the bay.

I was living on my boat at the time, I know the difference between halyards smacking against the mast and electronic noises.

John

 

[bbchien]

Fiberglass hull? Steel Hull? Mahoghany hull?

 

[John Baker]

Fiberglass hull? Steel Hull? Mahoghany hull?

Fiberglass hull.

John

 

[gismo]

When intercepted by any audio producing device most "normal" radar sounds like "ZZZZZZT" with a single blip occurring each time the radar sweeps past the device. So even if your mast could detect radar (not the least bit likely) it wouldn't sound like a "Ping". I suspect your hull and/or keel were picking up some sort of high powered sonar and the mast was radiating the sound.

 

[gkainz]

Since you were sailing right past the sub base, active sonar would be the most logical guess, in my opinion. However, since my only experience with subs was "mark as target - prosecute as necessary", that's just my 2cents.

 

[John Baker]

Since you were sailing right past the sub base, active sonar would be the most logical guess, in my opinion. However, since my only experience with subs was "mark as target - prosecute as necessary", that's just my 2cents.

I was about five miles out from the mouth of the bay. I'd had that happen a couple of times before. In the fog, it is kind of unnerving. the other times it was clear. I sold my boat about twenty years ago, so I don't know if it is still happening. I always had assumed it was radar of some sort, not sonar. I guess it could have been a submerged boat either going in or out.

John

 

[Joe B]

I was about five miles out from the mouth of the bay. I'd had that happen a couple of times before. In the fog, it is kind of unnerving. the other times it was clear. I sold my boat about twenty years ago, so I don't know if it is still happening. I always had assumed it was radar of some sort, not sonar. I guess it could have been a submerged boat either going in or out.

The attack sub I rode had an upward-looking active sonar, ostensibly for navigating under the ice pack in the arctic. That set emits so much energy it boils the water when the sub is at periscope depth. The sub also used it routinely during surfacing to make sure they weren't coming up under anything. Might have had something to do with what you heard.

 

[Ted]

The attack sub I rode had an upward-looking active sonar, ostensibly for navigating under the ice pack in the arctic. That set emits so much energy it boils the water when the sub is at periscope depth. The sub also used it routinely during surfacing to make sure they weren't coming up under anything. Might have had something to do with what you heard.

One of my friends has a story about when he operated radar on a sub. They were in some bay in Asia, and some hotshot was going about 40 kts through the water in a fairly substantial boat. My friend saw this coming and told the XO they were going to get hit. The XO didn't know how to respond, and so they just sat there when the ship struck the stern of the sub, causing the nose to come out of the water pretty high. Apparently the sub was undamaged, but the boat that hit it was not.

I can just see the captains of the respective vessels out there saying "That'll just buff out, there's no need to get the insurance companies involved in this."